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  #1  
Old 01-08-2007, 03:03 PM
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Engine clicking noise

Here's a confusing one... '85 300d NT.

Clicking noise emanates from the engine compartment when driving car under medium loads/speeds. It occurs in both forward and reverse. Strangely, if I drive the car lightly or at high loads the noise is not present (or extremely rare); it likes only marginal throttle and about 40-55 mph. Clicking noise is irregular and sounds very sharply (like breaking a stick) almost without pattern. Frequency of the noise can best be described as two nuts being disturbed irregularly in a tin can.

Noise occurs irrespective or road conditions, temperature, etc. It occurs one or two times in reverse if I punch it then back off. More commonly, it occurs in drive when going on straight-aways (country roads) at 40-55 mph when I'm NOT accelerating or decelerating, just maintaining speeds on flat runs. If I accelerate the throttle further the car will drive to higher speeds and maintain them without the noise reoccurring. Noise does not occur in neutral when revving he engine.

I inspected the engine compartment and could not find anything obvious. Checked air cleaner mounts and most of the frame mounted accessories. Could it be the engine mounts, the fan hitting the shroud or a belt driven accessory? Could it be an internal engine noise? Could an old exhaust cause this noise?

This noise has not “suddenly” occurred; it has developed and become more frequent. Any thoughts?

Thanks,

ATLD.

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  #2  
Old 01-08-2007, 06:03 PM
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Ticking

I had vibration that sounded like you discribe yours. I turned out to be the bolts between the engine and transmission. Some were gone others were loose. Hope it helps. Jim
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  #3  
Old 01-08-2007, 06:09 PM
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Could be so many things.

Perhaps flex disk, front sway bar links, or air filter damper bolts?
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  #4  
Old 01-08-2007, 06:21 PM
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Exhaust manifold gasket?
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Old 01-08-2007, 06:42 PM
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Worst Case!! cracked crank ( happened to me )
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  #6  
Old 01-08-2007, 07:06 PM
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How about instrument cluster odometer gears skipping teeth?
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Old 01-09-2007, 10:34 AM
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the fan shroud on these is totally adjustable from car to car. make sure that the gap is even all the way aroun- aboput 1/2" on mine. the shroud is held in place with 2 clips on the top of the radiator. removal will allow free movement of fan- side to side and up-down. center it up and replace clips.

good luck,mo
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  #8  
Old 01-09-2007, 05:14 PM
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Thank you for your replies. I will loom into your suggestions. I really hope that it's the fan shroud. I will put some light onto that hopefully tonight. Unfortunately the sound occurs only when the car is driven so it is difficult to pinpoint the source it it's interference due to engine mount deflection under load.

I'll check the engine/tranny bolts. Strange if they decide to vibrate loose after 250k mi.

I had checked the air filter before; I'm confident it's tight. Where are the flex-disks and is there a test fo runout etc?

I have plans to replace the exhaust with a TimeValve S.S. system very soon. That should eliminate the exhaust as a suspect.

ConnClark, was the crank failure noise intermittent for 5+k mi with increasing frequency; or was is a click than break deal? Can you describe your symptom in more detail?

I'll listen to my IC more carefully, but am pretty sure the noise is comming from the engine compartment. It's loud enough to be a serious interference slap rather than a gear slip.

I'll inspect the fan shroud tonight for evidence of fan contact.

Thanks everyone and hopefully I'll find a cause before something more serious occurs.
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Old 01-09-2007, 06:29 PM
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I only had my clicking noise for 70 miles or so. Then I sold the car.

I was driving along and I heard a *tink* noise like I had run over some bailing wire. When I pulled off the highway when I got into town there was a loud clicking once my rpms dropped close to idle speed. The clicking noise was related to the rpm. It disappeared completely about 1800 rpm.
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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png
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  #10  
Old 01-10-2007, 09:15 AM
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I'm not too sure how comforting it is to know that you sold your car because it made a clicking noise...

ATLD
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  #11  
Old 01-10-2007, 11:44 AM
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I had a mechanic take a look and he found the cracked crank.

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green 85 300SD 200K miles "Das Schlepper Frog" With a OM603 TBO360 turbo ( To be intercooled someday )( Kalifornistani emissons )
white 79 300SD 200K'ish miles "Farfegnugen" (RIP - cracked crank)
desert storm primer 63 T-bird "The Undead" (long term hibernation)

http://ecomodder.com/forum/fe-graphs/sig692a.png
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